DibbleWhen to plant sunflowers in Zone 4
In Zone 4, the last spring frost usually passes around May 10 and the first fall frost arrives around September 21, leaving about 134 frost-free days. The windows below are computed from those frost dates, with the same math the Dibble app uses.
Cool climate with a brief warm window. Indoor starts and season extension help.
Planting windows for sunflowers in Zone 4
| Task | Window |
|---|---|
| Direct sow | May 10 to May 24 |
| Estimated harvest | Jul 29 to Aug 19 |
The harvest estimate counts 80 days to maturity, then a picking window of about 21 days. These windows use typical frost dates for Zone 4; Dibble pins them to your exact ZIP code.
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Sunflower in a Zone 4 season
Zone 4 gives about 134 frost-free days. Sunflower needs roughly 80 days from sowing. That leaves about 54 days of slack, enough for one full crop with a little room for a cold spring.
Sowing every 14 days, Zone 4 has room for about 4 plantings.
How to grow sunflowers
Sow sunflowers around your last frost date. Stagger plantings every couple of weeks for blooms all summer.
Companion plants
Good neighbors for Sunflower:
Better kept apart:
Sunflower in other zones
Not in Zone 4? Pick your zone for the same dated windows.
Keep exploring
Sunflower: the full growing guide · The Zone 4 planting calendar · Every crop and zone
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Dates are estimates based on typical frost dates for the zone. Your yard has its own microclimate, so use them as a starting point and adjust as you learn your space.